Method for calculating the operating time of hydraulic components

ABSTRACT

An actual operating time is determined by an approximation method within the scope of the method for determining the actual operating time of a hydraulic, electrohydraulic or electric component of a motor vehicle or of a working machine within a reference time or a monitoring period.

According to the preamble of claim 1, this invention relates to a methodfor calculating the operating time of hydraulic, electrohydraulic orelectric components of a motor vehicle or of a working machine.

Certain hydraulic, electrohydraulic or electric components of a motorvehicle or of a working machine, such as valves or pumps, usually arenot laid out with fatigue limit so that a maximum admissible operatingtime (ED) is indicated within a reference period. To make possible theelimination of damage of said components due to permanent control, thecontrol devices or control software concerned must know the actualoperating time (ED) at the moment at which a control signal isgenerated.

For determining the actual operating time, it is required that onecomponent be controlled beginning from the present moment up to themoment lying back by the reference period. If the control devicegenerates a control signal, for example, every 5 ms, the operating timein a reference period of 60 seconds, for example, 12000 individualvalues, has to be taken into account for calculating. Therefore, toexactly determine the operating time, the values have to be separatelystored for each component. The storage place, as a rule, is notavailable in a control device for reasons of cost.

The problem on which this invention is based is to outline a method fordetermining the actual operating time of a hydraulic, electrohydraulicor electric component of a motor vehicle or of a working machine, whichmakes determining the actual operating time as precisely as possible incase of storage place need clearly smaller than the method according tothe prior art.

This problem is solved by the features of claim 1. Other variationsresult from the sub-claims.

It is accordingly proposed that an approximation method is used forcalculating the actual operating time.

In particular, the monitoring period or the reference period is dividedinto separate intervals or time windows which correspond to a certainnumber of program or control runnings; there is coordinated with eachtime window one value which is increased by the momentary controlperiod. The operating time then results as sum of the values of theindividual time windows; it is possible to provide one or more windowswith weighting factors.

The inventive method considerably reduces the number of values to bestored; it corresponds to the number of time windows and the storedmeter.

The method is explained in detail herebelow with reference to theenclosed figures.

FIG. 1 shows a time/signal diagram with the corresponding time windowsfor a general case; and

FIG. 2 is a time/signal diagram with the inventive time windows for aconcrete embodiment explained herebelow.

As shown in FIG. 1, according to the invention, the monitoring orreference period is divided into individual time windows, each timewindow having the length of k control or program runnings. The number kcan be defined based on the precision of calculation desired to beachieved. The higher k is, the lower the precision obtainable, sinceseveral values are combined.

The operating time of the component concerned during one of said timewindows is stored as one value, the value of the actual time windowbeing increased with each program running by the momentary control timeof the component. After k program runnings, which are detected by ameter n, the time window just expired moves to the second place, themeter is reset and the value of the time window lying farthest back isdeleted whereby the storage place that has become free is available forrecording the operating time in the new actual time window. The numberof time windows does not change all together.

According to the invention, the operating time within the monitoringperiod is calculated by summing up all values of the individual timewindows. One variant of the invention provides weighting of theindividual window by means of an appertaining weighting factor.

According to a special advantageous variant of the invention, the timewindow lying farthest back loses influence as the level (meter n) of theactual time window increases. The time window lying farthest back isweighted with the factor (1−n/k), n representing the meter of the actualtime window.

The determination of the number of time windows needed for storing thetotal operating time in the monitoring period results from the followingformula:${{{Number}\quad{of}\quad{time}\quad{windows}} = {\left( \frac{T_{u}/T_{p}}{k} \right) + 1}},{with}$

-   T_(u)=monitoring period-   T_(p)=program running time-   k=number of values per time window

There results, for example, for a program running time of 5milliseconds, a monitoring period of 60 seconds and the value 1000 forthe factor k 13 time windows with a length of 5 seconds each. Thediagram corresponding to these values is object of FIG. 2

As already explained, the precision of the calculation of the operatingtime is mainly determined by the factor k. Besides, the maximum possibledivergence of the calculated value from the real value occurs preciselyat the moment of the program running when the condition n=k/2 has beenmet. The typical maximum values for the errors occurring in such asituation are in the order of ±2.0% and can only be reached by a quitespecific control signal for k=1000 and 13 time windows; for the normalcase, on the other hand, an error of about ±1.0% is to be expected, acompromise having to be reached between precision and storage need.

Reference Numerals

-   T_(u) monitoring period-   t_(p) program running time-   k number of values per time window-   n meter

1-4. (canceled)
 5. A method for determining an actual operating time of one of a hydraulic, electrohydraulic and electric component of a motor vehicle and of a working machine within one of a reference time and a monitoring period, in which the actual operating time is determined by means of an approximation method, wherein one of the monitoring period or the reference time is divided into one of separate intervals or time windows which correspond to a specific number k of program or control runnings, there being coordinated with each time window one value which is increased by a momentary, actual control time and then stored and then after k program runnings, which are detected by a meter n, the time window just expired moves to a second place, a new window is generated, the meter n is reset and the value of a time window lying farthest back is deleted, the operating time being calculated within the monitoring period by summing up all values of the individual time windows.
 6. The method according to claim 5, wherein the values of one or more time windows is weighted by means of a weighting factor.
 7. The method according to claim 6, wherein the time window lying farthest back is weighted with a factor (1−n/k).
 8. A method for determining an actual operating time of one of a hydraulic, electrohydraulic and electric component of a machine within one of a reference time and a monitoring period, the actual operating time is determined by an approximation method comprising the steps of: dividing one of the monitoring period or the reference time into one of separate intervals and time windows which correspond to a specific number k of program or control runnings; coordinating each of the separate intervals and time window with a value; increasing each value by a momentary actual control time; storing the increased value; moving the time window just expired to a second place after the specific number k has been reached, as detected by a meter n; generating a new window after the time window is moved; resetting the meter n and deleting the time window lying farthest back; calculating the operating time within the monitoring period by summing up all the values of the individual time windows. 